1. Field of the Invention
The present invention relates to a process for breaking emulsions comprising water and oil using microorganisms, and to microorganisms used therefor.
2. Related Art
Complex water-in-oil (W/O) and oil-in-water (O/W) emulsions are generated in various petroleum recovery and refining process. Prior to further processing of the petroleum phase, the emulsions must be broken and aqueous layer separated from the oil. This separation is troublesome and difficult, so that destabilization of emulsions is a perpetual and costly problem for which better solutions are continuously sought.
W/O emulsions are generated during recovery and processing of petroleum crudes. Surfactants, steam and/or water is used to form an emulsion to improve the recovery rate as well as increase fluidity and movement. In an oil refining, stable emulsion are formed in a process to remove the moisture and highly concentrated salts contained therein.
O/W emulsions are generated from various stage, so that in the crude oil recovery process, the washing process of crude oil transport tankers and storage tanks, oil refining process and handling process for storage of petroleum products and so forth. In addition, excess amounts of industrial waste water emulsions are produced from food processing manufactures, dust control plants and oil handling factories. The industrial and domestic waste water may cause a severe environmental pollution. In addition to difficulties encountered in handling these emulsions due to their high viscosity, it is also difficult to treat these emulsions in the form of waste water. In order to treat emulsified waste water, it is first necessary to break emulsions and separate it into water and oil components.
In the case of carrying out a chemical reaction in a two-phase system consisting of an oil phase and a water phase, the formation of an emulsion by addition of surfactant is known in, for example, emulsion polymerization, and due to the considerable problems encountered when trying to remove the surfactant after reaction, the use of surfactant has been limited.
Moreover, in the case of bio-refining technology in which desulfurization, demetalization and denitrification and so forth are performed on crude oil and petroleum products by applying biotechnology, an emulsion is formed by biosurfactants produced by the microorganisms used. Although biosurfactants promote the bio-processing reactions, since there are serious problems encountered when trying to separate the oil and water components following completion of the reactions, effective means for breaking the emulsion have to be found. Various other means of solving these problems are being proposed in various ways depending on particular cases.
Processes for breaking emulsions known in the prior art include processes that use an inorganic or organic demulsifier, and processes that treat emulsions mechanically. An example of a process that uses an inorganic emulsion breaking agent is described in Japanese Unexamined Patent Publication No. 54-156268, which process uses an inorganic salt such as sodium chloride or potassium chloride. A process using a mixture of aluminum chloride and iron (III) chloride as a coagulating agent is described in Japanese Unexamined Patent Publication No. 50-116369, while a process using aluminum sulfate or iron chloride and so forth as coagulating agent is described in Japanese Unexamined Patent Publication No. 46-49899. In addition, Japanese Unexamined Patent Publication No. 46-33131 describes a process using ferric sulfate.
In addition, as an example of a process using an organic substance, Japanese Unexamined Patent Publication No. 54-10557 describes a process wherein an emulsion is broken by filtration after lowering the viscosity of the emulsion by using a polyoxyethylene alkylphenyl ether-based additive. On the other hand, as an example of mechanical treatment process, Japanese Unexamined Patent Publication No. 53-91462 describes a process wherein an emulsion is filtered by a filter having a demulsification function.
On the other hand, Japanese Unexamined Patent Publication No. 57-187098 describes a process wherein suspended solids including Kaolin clay are treated using microorganisms belonging to the genus Aeromonas after which COD, BOD and so forth are lowered by aggregation of those organic substances. In addition, a process wherein industrial waste water containing specific organic compounds is treated using microoraganisms belonging to the genus Aeromonas having an ability to assimilate and decompose said specific organic compounds are described in Japanese Unexamined Patent Publication No. 52-116647, Japanese Unexamined Patent Publication No. 52-11646, Japanese Unexamined Patent Publication No. 51-133954, and Japanese Unexamined Patent Publication No. 51-133475.
However, a process in which emulsions composed of water and oil are broken by using Alteromonas species bacteria, Rhodococcus species bacteria or Aeromonas species bacteria is not known in the prior art.